Chen is also charged with assaulting a police officer while in custody, authorities said. His defense attorney, Danielle Eaddy, said Chen was injured while in police custody and appeared to have two bruises on his forehead.

Investigators said Chen had been staying with the family for about a week prior to Saturday’s killings.

Two girls, 9-year-old Linda Zhuo and 7-year-old Amy Zhuo, were pronounced dead at the scene, along with 18-month-old William Zhuo, police said. They were all found in a back bedroom, police said.

Their brother, 5-year-old Kevin Zhuo and their 37-year-old mother, Qiao Zhen Li, were found in the kitchen and taken to hospitals, where they also were pronounced dead, police said.

NYPD Chief of Department Philip Banks III said the five “were cut and butchered with a kitchen knife.” Banks said the victims died of stab wounds to their necks and torsos and that Chen had implicated himself in the killings.

“The sister arrives at the location with her husband and they bang on the door and they bang on the door,” At some point, Banks said Chen “opens the door and they see that he’s covered in blood.”

The couple fled and called 911. Police quickly responded to the home and arrested Chen at the scene.

Banks said police have yet to determine a motive for the massacre.

“He made a very short comment that since he’s been in this country everybody seems to be doing better than him, and that was a short comment,” he said. “We’re not really sure what that means.”

Investigators believe Chen came from Chicago to stay with his cousin’s family a week or so ago.

On Saturday night, Sunset Park neighbors heard victim Li’s screams. She had been home the children while her husband, Yi Lin Zhuo, was at work.

Relatives who came to the scene moments after the massacre encountered Chen in bloody clothes. They told police Chen said, “I know I am done.”

Neighbors had taken little note of Chen during his brief stay with the family. Neighbor Katrina He said she would just see him sitting outside smoking.

On Monday, Katrina He and the other residents moved out of the multi-family murder scene. The thought of what had happened in the building was too much to live with.

“All people will be moved out,” said neighbor Yun Wang. “Nobody living here. Nobody want to stay.”

Banks said Chen was fluent only in Mandarin Chinese almost a decade after coming to the United States as a teenager. Neighbors and relatives said he was unemployed after being fired from a string of restaurant jobs.